Free admission to all residents with a Milton Keynes postcode. Bletchley Park was once Britain's best kept secret but is now a heritage site.
Open Thurs 6th Sept 9.30-1700. Tours 11.00 & 1400
Fri 7th Sept 9.30-1700 . Tours 11.00 & 14.00
Sat 8th sept 10.30-1700
Sun 9th Sept 10.30-1700
Lots of other free events listed for Heritage week.
Worth checking in your area. http://www.heritageopendays.org.uk